When calling recover() from getarg(), also check to see if the first

character of the argument being processed isn't '\0'.

This fixes problem with backgammon exiting abnormally when you answer 'y' to
the question it asks if you need instruction for the game.

2.2 cnadidate, maybe?

games/backgammon/common_source/subs.c

@@ -376,7 +376,7 @@ register char	***arg;
 		}
 		s++;
 	}
-	if (s[0] != 0)
+	if (s[0] != 0 && s[0][0] != '\0')
 		recover(s[0]);
 }